In order to detect a living body state of a person, for instance, whether or not it is in an activated state (awakening state) or in a sleeping state, measurement of a brain wave and analysis of the brain wave pattern have been conventionally carried out. However, the measurement of a brain wave must be conducted under circumstances to restrict a human ordinary behavior such as necessity of setting a brain wave electrode or an ocular potential electrode on the head of a testee, and it is difficult to evaluate a living body state in a highly scientific level at the time of driving various transportation devices such as a car, a train or the like for instance without imposing a burden on the driver.
Whereas, monitoring a living body state (mental-and-physical state) of a driver while driving has been attracted recently as a countermeasure to prevent accident, and, for instance, a technology to use a heartbeat or a pulse beat for chaos analyzing it to monitor a living body state in Patent Document 1 and Patent Document 2. According to the technologies disclosed in Patent Documents 1 and 2, it is possible to evaluate a living body state of a driver easily without setting a large-scale device for brain wave measurement on the head.
Patent Document 1: Japanese Patent Application Laid-open No. Hei 9-308614
Patent Document 2: Japanese Patent Application Laid-open No. Hei 10-146321